Coaches at the University of Missouri divided players into small groups at a preseason football practice last year for a team-building exercise. One by one, players were asked to talk about themselves – where they grew up, why they chose Missouri and what others might not know about them.

As Michael Sam, a defensive lineman, began to speak, he balled up a piece of paper in his hands.

“I’m gay,” he said.

With that, Sam set himself on a path to become the first publicly gay player in the National Football League.

“I looked in their eyes, and they just started shaking their heads – like, finally, he came out,” Sam said Sunday, the first time he spoke publicly about his sexual orientation.

Sam, a 6-foot-2, 260-pound senior, went on to a stellar season for Missouri, which finished 12-2 and won the Cotton Bowl. He was named a first-team All-American. He was the defensive player of the year in the Southeastern Conference, widely considered the top league in college football. Teammates voted him Missouri’s most valuable player.

Now Sam enters an uncharted area of the sports landscape. He is making his public declaration before he is drafted, to the potential detriment to his professional career. And he is doing so as he prepares to enter a league with an overtly macho culture, where controversies over homophobia have attracted recent attention.

As the pace of the gay rights movement has accelerated drastically in recent years, the sports industry has seen relatively little change, with no publicly gay male athletes in the NFL, the National Basketball Association, the National Hockey League or Major League Baseball. Against this backdrop, Sam could become a symbol for the country’s gay rights movement or a flashpoint in a football culture war – or both.

Sam, 24, is projected to be chosen in the early rounds of the NFL draft in May, ordinarily an invitation to a prosperous professional career. He said he decided to come out publicly now because he sensed that rumors were circulating.

“I just want to make sure I could tell my story the way I want to tell it,” said Sam, who also spoke with ESPN on Sunday. “I just want to own my truth.”

But the NFL presents the potential for unusual challenges. In the past year or so, the league has been embroiled in controversies ranging from anti-gay statements from players to reports that scouts asked at least one prospective player if he liked girls.

Although Sam’s professional prospects are far from certain, several NFL draft forecasters have predicted that he will be chosen in the third round. (Thirty-two players are selected in each round.) Rarely are players who are drafted that high cut by teams, and often they become starters, sometimes in their rookie year.

Between now and the draft, Sam plans to attend the scouting combine, where players are put through a gantlet of physical and mental tests to judge their readiness for the NFL. Sam might be considered too small for a professional defensive end, meaning he would have to learn to play as an outside linebacker.

But it is reasonable for Sam to wonder what sort of impact – positive or negative – his declaration will have on his professional prospects.

“I’m not naïve,” Sam said. “I know this is a huge deal, and I know how important this is. But my role as of right now is to train for the combine and play in the NFL.”

Sam said he graduated from Missouri in December as the only member of his family to attend college.

He grew up in Hitchcock, Texas, near the Gulf Coast about 40 miles southeast of Houston, the seventh of eight children of JoAnn and Michael Sam. It was a difficult childhood; three of his siblings have died, and two brothers are in prison, Sam said. He was raised mostly by his mother, and he spent some years with another family who took him in. All have been supportive of his coming out, Sam said.

Sam said he began to wonder if he was gay in his early teens, though he had a girlfriend in high school. It was after he arrived at Missouri in 2009 that he realized for certain that he was gay.

Sam came out to two of his friends on the team, L’Damian Washington and Marvin Foster, about a year ago. It was not a huge surprise. Washington was with Sam when Sam said he needed to go pick up a friend. He told Washington that the friend was gay and asked Washington if that would bother him. Washington said no, and Sam came out to him.

“Once I became official to my teammates, I knew who I was,” Sam said. “I knew that I was gay. And I knew that I was Michael Sam, who’s a Mizzou football player who happens to be gay. I was so proud of myself and I just didn’t care who knew. If someone on the street would have asked me, ‘Hey, Mike, I heard you were gay; is that true?’ I would have said yes.”

No one asked.

“I guess they don’t want to ask a 6-3, 260-pound defensive lineman if he was gay or not,” Sam said. And he laughed.